Daly
9.1 Precipitation on surface water

The volume recognised in the water accounting statements of 103 ML represents the total volume of rainfall that fell on Copperfield Dam during the 2012–13 year.

This volume does not include precipitation on rivers as for the 2012–13 year it has been accounted for in 9.4 Runoff to surface water. In the 2011–12 year the volume representing precipitation on rivers was included in this line item.

Monthly precipitation grids, Australian Hydrological Geospatial Fabric—waterbody feature class and stream network feature class, Australian Water Resources Information System—water storages.

The Bureau of Meteorology.

Monthly precipitation grids were produced using daily data from approximately 6,500 rain gauge stations and interpolated to a 0.05⁰ (5 km) national grid (Jones et al. 2007).

The precipitation at Copperfield Dam was estimated from the proportionally weighted average of grid cells that intersected the water feature. The volume was then estimated by multiplying by the surface area of the storage. In this case, a static surface area value from the Australian Hydrological Geospatial Fabric was used.

The precipitation estimates were subject to approximations associated with interpolating the observation point data to a national grid as detailed in Jones et al. (2007). 

The use of the static Australian Hydrological Geospatial Fabric waterbody feature class surface area is an approximation only. It represents the storage at total capacity and therefore is likely to result in an overestimation of precipitation on the storage.

Derived from modelled data. The uncertainty estimate was not quantified.